Colon Cancer Prevention (cont.)

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Calcium supplements have been shown in animal and human studies to decrease the number of pre-cancerous polyps. Fruits and vegetables contain many chemicals that inactivate cancer-causing chemicals (carcinogens). Obesity, a sedentary life style, cigarette smoking, and high red meat consumption have been linked to an increased risk of
colorectal cancer. In a large study of nurses, those who took multivitamins that contained folic acid for decades had less
colorectal cancer than women who did not take multivitamins.

These measures are considered only "probably" effective because long-term, large-scale, properly designed clinical trials have yet to be performed to establish conclusively that these measures actually prevent
colorectal cancer.

Doctors are willing to prescribe an agent without conclusive proof of its effectiveness as long as it is safe. In many instances, conclusive proof may be many years away.

What prevention measures have been found to be ineffective?

Anti-oxidants are believed to have anti-cancer effects, but clinical trials using the anti-oxidant vitamins C and A has shown no benefit in preventing
colorectal cancer.

Many agents or measures that are promising because they have theoretical benefits fall short of expectations when subjected to rigorous clinical trials.